Photographic lens system for compact cameras

ABSTRACT

A photographic lens system for compact cameras comprising a first, second, third, fourth and fifth lenses, the first lens being a positive meniscus lens arranged to be convex toward the object side, the second lens being a biconcave lens, the third lens being a positive lens, the fourth lens being a biconvex lens, the fifth lens being a negative meniscus lens arranged to be convex toward the image side, the photographic lens system being arranged to make aberrations, especially astigmatic difference and positive distortion, small by giving a large thickness to the fourth lens located on the image side by the stop and, at the same time, arranged to have a field angle of 70° or more.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a photographic lens system for compactcameras with a field angle 70° or more and aperture ratio F/3.5.

(b) Description of the Prior Art

Tessar type lens systems and various other types of lens systems areknown as photographic lens systems for compact cameras. However, thefield angle of known photographic lens systems is about 60° to 65° atthe largest.

Generally, for photographic lens systems, astigmatism and distortioncome into problem when it is attempted to make the field angle large.Therefore, even when curvature of field is corrected by making Petzval'ssum small, astigmatic difference increases. For photographic lenssystems for compact cameras, a very high price is not desirable.Therefore, it is not preferable to correct astigmatic difference byadopting a complicated lens configuration. Even when it is permitted tomake the lens configuration complicated, lenses should be arranged in avery limited space because the overall length of the lens system cannotbe made long in case of lens systems for compact cameras and,cosequently, the lens configuration cannot be made complicated inpractice. Therefore, for photographic lens systems for compact cameras,it is difficult to correct astigmatic difference.

In recent years, photographic lens systems of so-called telephoto typewith comparatively simple lens configuration is known, i.e., such lenssystems are arranged that the front lens group has positive power andrear lens group has negative power in order to make the overall lengthof the lens system short. For example, the lens system disclosed inJapanese published examined patent application No. 50248/81 is known asa lens system arranged as descrived in the above.

However, in case of the above-mentioned lens system, the front lensgroup has strong positive power and, therefore, positive distortion iscaused by the front lens group. Besides, as a negative meniscus lenswhich is convex toward the image surface is arranged on the image sideof the stop, opsitive distortion occurs largely at said negativemeniscus lens when the field angle becomes larger and the incident angleof principal ray on said negative meniscus lens becomes larger. It isdifficult to correct the above-mentioned positive distortion.

Besides, the lens system disclosed in Japanese published unexaminedpatent application No. 95207/81 is known as a wide-angle photographiclens system of telephoto type wherein the rear lens group consists oftwo lens components, i.e., a positive lens component and a negative lenscomponent. However, the field angle of said lens system is about 60°.

When a compact camera is arranged that the stop serves also as theshutter, it is practically difficult to arrange the mechanism so as tomove the stop. Therefore, lens systems for compact cameras are arrangedthat the stop is fixed and lens components are partially moved for thepurpose of focusing. Especially, the focusing method to move the frontlens or front lens group is adopted in most cases. As other knownfocusing methods, a method to move the intermediate lens is disclosed inJapanese published unexamined patent application No. 76148/79 and amethod to move the rear lens is discolsed in Japanese publishedunexamined patent application No. 133711/81. However, in case of thesefocusing methods, it is impossible to perfectly correct variation ofaberrations.

SUMMARY OF THE INVENTION

It is, therefore, a primary object of the present invention to provide aphotographic lens system for compact cameras comprising a front lensgroup and a rear lens group and arranged to make astigmatic differencesmall and to correct positive distortion by arranging a thick convexlens in rear of the stop, the photographic lens system for compactcameras being arranged that the field angle is 70° or more, apertureratio is F/3.5 and overall length of the lens system is short.

When the above-mentioned thick convex lens arranged in rear of the stopis regarded as two thin plano-convex lenses and a plane-parallel platewhich are arranged integrally, study into the state of aberrations whena plane-parallel plate is arranged in rear of the stop enables to judgethe state of aberrations of a lens system in which a thick convex lensis arranged in rear of the stop of the lens system.

Generally, when converging rays pass through a plane-parallel plate,positive curvature of field is caused and the value thereof is expressedby the following formulas: ##EQU1## where, reference symbol d representsthe thickness of the plane-parallel plate, reference symbol n representsthe refractive index of the plane-parallel plate, reference symbol irepresents the angle of incidence, and reference symbol i represents theangle of refraction.

As positive astigmatic difference is caused by the plane-parallel plateas described in the above, it is possible to reduce astigmaticdifference by selecting the thickness of the plane-parallel plate as anadequate value.

Besides, distortion is caused by the above-mentioned plane-parallelplate and the value thereof is expressed by the following formula.##EQU2##

As tan i<0 in the formula shown in the above, it becomes Δy'<0 andnegative distortion occurs. Therefore, by the plane-parallel plate, itis possible to correct positive distortion caused by the front lensgroup with positive power and by the final lens.

Due to the above-mentioned reason, it is possible to correct astigmaticdifference and distortion by arranging a thick lens in rear of the stopand selecting the thickness thereof as an adequate value.

Due to the reason described so far, the photographic lens system forcompact cameras according to the present invention is arranted as a lenssystem with five-component five-element lens configuration comprising afirst, second, third, fourth and fifth lenses, the first lens being apositive meniscus lens arranged to be convex toward the object side, thesecond lens being a biconcave lens, the third lens being a positivelens, the fourth lens being a biconvex lens, the fifth lens being anegative meniscus lens arranged to be convex toward the image side, thephotographic lens system according to the present invention beingfurther arranged that the value of the thickness d₇ of the fourth lenslocated just in rear of the stop is selected in the range defined by thecondition (1) shown below so that astigmatic difference and distortionare corrected favourably:

    0.15f<d.sub.7 <0.4f                                        (1)

where, reference symbol f represents the focal length of the lens systemas a whole.

If d₇ becomes smaller than the lower limit of the condition (1), thecorrecting action of the convex lens (the fourth lens) becomes weak andit is impossible to correct astigmatic difference and positivedistortion. If d₇ becomes larger than the upper limit of the condition(1), the lens system becomes large and it is not suitable as a lenssystem for compact cameras.

The photographic lens system having the lens configuration described inthe above and arranged to fulfill the condition (1) enables to attainthe object of the present invention. When, however, it is arranted tofurther fulfill the conditions (2) and (3) shown below, it is possibleto obtain a more favourable photographic lens system.

    1.7<n.sub.2                                                ( 2)

    0.35f<|f.sub.5 |<0.6f,f.sub.5 <0         (3)

where, reference symbol n₂ represents the refractive index of the secondlens, and reference symbol f₅ represents the focal length of the fifthlens.

To reduce curvature of field, Petzval's sum should be made small. If,however, Petzval's sum is made too small, astigmatic differenceincreases in the portion of intermediate field angle when astigmaticdifference near the portion of the largest field angle is correctedfavourably at the time of correction of astigmatic difference by meansof the fourth lens. To select Petzval's sum as an adequate value bytaking the above-mentioned point into consideration, it is preferable toselect the refractive index n₂ of the second lens so as to fulfill thecondition (2). If n₂ becomes smaller than the lower limit of thecondition (2), Petzval's sum becomes too small and it is impossible tocorrect astigmatic difference in the portion of intermediate fieldangle.

To obtain a lens system with more favourable performance by limitingpositive distortion to be caused, it is preferable to select the focallength f₅ of the fifth lens so as to fulfill the condition (3) shown inthe above. If |f₅ | becomes smaller than the lower limit of thecondition (3), positive distortion increases. If |f₅ | becomes largerthan the upper limit of the condition (3), the overall length of thelens system becomes long and it is not suitable for a lens system forcompact cameras.

When the power of the fifth lens is defined to fulfill the condition (3)as described in the above, spherical aberration will curve largely whenthe absolute value |r₉ | of the radius of curvature of the sirface onthe object side of the fifth lens becomes small. Besides, when |r₉ |becomes very large, the radius of curvature of the surface on the imageside of the fifth lens also becomes large because the focal length f₅ ofthe fifth lens is defined to a certain range shown in the above. As aresult, the surface on the image side of the fifth lens becomes nearlyvertical to rays. In consequence, distortion increases and it becomesimpossible to correct it. Therefore, it is preferable to select |r₉ | soas to fulfill the condition (4) shown below.

    0.25f<|r.sub.9 |<0.35f                   (4)

If |r₉ | becomes smaller than the lower limit of the condition (4), itis impossible to correct the curve of spherical aberration. If |r₉ |becomes larger than the upper limit of the condition (4), it isimpossible to correct positive distortion.

When r₉ is defined as desctibed in the above, it is preferable to selectthe radius of curvature r₈ of the surface on the image side of thefourth lens in the range defined by the condition (5) shown below inorder to make the lens system more compact.

    0.4f<|r.sub.8 |<0.5f,r.sub.8 <0          (5)

If |r₈ | becomes smaller than the lower limit of the condition (5),spherical aberration will be undercorrected. If |r₈ | becomes largerthan the upper limit of the condition (5), the airspace between thefourth and fifth lenses should be made large in order to ensuresufficient intensity of light in the marginal portion. As a result, theoverall length of the lens system increases, and this is not desirable.

To make the field angle wide and, at the same time, to make the overalllength of the lens system short in case of the lens system with the lensconfiguration as shown in FIG. 1, it is preferable to arrange that thepower of the front lens group (the first, second and third lenses) andpower of the lens (the fifth lens) arranged on the image side in therear lens group are made strong. When, however, the power of the frontlens group is made strong, curvature of field increases, and it isimpossible to obtain favourable quality of image to the marginalportion. When this point is taken into consideration, more preferableway is to make the power of the front lens group weak by balancing thepower of the front lens group with the power of the positive lens (thefourth lens) in the rear lens group. Thereofre, it is preferable toarrange so that the focal length f₁₂₃ of the front lens group and focallength f₄ of the fourth lens fulfill the following condition.

    2.0<f.sub.123 /f.sub.4 <4.0

If f₁₂₃ /f₄ becomes smaller than the lower limit of the condition shownin the above, the power of the front lens group becomes strong andcurvature of field increases. If f₁₂₃ /f₄ becomes larger than the upperlimit of the condition shown in the above, the overall length of thelens system becomes long, and this conflicts with one of the objects ofthe present invention, i.e., to make the lens system compact.

Now, the focusing method of the photographic lens system according tothe present invention is described below. Generally, the followingmethods are considered as the focusing methods: (1) the method toadvance the lens system as a whole, (2) the method to advance the frontlens group, (3) the method to advance the first lens, (4) the method tomove the fourth lens, i.e., the intermediate lens, toward the imageside, and (5) the method to move the fifth lens i.e., the rear lensgroup, toward the image side. Besides, combinations of the focusingmethods (1) to (5) may be also considered.

Out of the above-mentioned methods, the methods to move partial lenscomponents in the lens system necessarily cause variation of aberrationsat the time of focusing. For example, when the lens system is focused bythe method (3) to advance the front lens, spherical aberration becomesnegative and curvature of field becomes positive when the lens system isfocused on an object at a short distance. In case of the focusing methodto move the rear lens (method (5)), i.e., the method to move thenegative lens arranged on the image side of the stop like the knowfocusing method disclosed in Japanese published unexamined patentapplication No. 133711/81 mentioned before, spherical aberration becomesnegative and curvature of field also becomes negative when the lenssystem is focused of an object at a short distance.

As the correlation between spherical aberration and curvature of field,it is desirable that the image surface comes to a position close to theoptical image position determined by spherical aberration. In case offocusing methods to move partial lenses in the lens system, it isimpossible to bring the image surface close to the optical imageposition determined by spherical aberration. Even in cace that thedirection of variation of spherical aberration becomes the same as thedirection of variation of curvature of field at the time of focusing asin case of the focusing method to move the rear lens, when the amount ofvariation of spherical aberration and amount of variation of curvatureof field become different from each other, the marginal portion of theimage surface does not always come to the optical image positiondetermined by spherical aberration because of curvature of field.

In case of the lens system according to the present invention, a lenscomponent to be moved for the purpose of focusing is provided in each ofthe front lens group on the object side of the stop and the rear lensgroup on the image side of the stop, and it is so arranged that thesigns of refractive powers of the above-mentioned movable lenscomponents become different from each other. It is thereby arranged thatthe variation of curvature of field, which largely vary when the movablelens components are moved, becomes a small and adequate value as a wholeand, moreover, the direction of variation of curvature of field becomesthe same as the direction of variation of spherical aberration to becaused by the movement of the movable lens components. Thus, the lenssystem according to the present invention is arranged that the amount ofvariation of curvature of field becomes equal to the amount of shiftingof the optical image position determined by spherical aberration, saidoptical image position being shifted by variation of sphericalaberration, and is thereby arranged that a favourable image is obtainedup to the short distance. In this case, it is preferable to arrange thatboth of the movable lens components have surfaces which are concentricin respect to the stop and, especially, it is preferable to arrange thatthose movable lens components have meniscus shapes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional view of the photographic lens system forcompact cameras according to the present invention;

FIGS. 2 through 14 respectively show graphs illustrating aberrationcurves of Embodiments 1 through 13 of the photographic lens systemaccording to the present invention;

FIG. 15 shows a sectional view of a lens system arranged by replacingthe fourth lens in the lens system according to Embodiment 1 with twolenses which are located by leaving an airspace between them;

FIG. 16 shows graphs illustrating aberration curves of the lens systemshown in FIG. 15;

FIG. 17 shows graphs illustrating aberration curves obtained when thelens system according to Embodiment 13 is focused on an object at ashort distance by moving the first and fifth lenses;

FIG. 18 shows graphs illustrating aberration curves obtained when thelens system according to Embodiment 13 is focused by moving the fifthlens; and

FIG. 19 shows graphs illustrating aberration curves obtained when thelens system according to Embodiment 13 is focused by moving the firstlens.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, preferred embodiments of the photographic lens system for compactcameras according to the present invention described so far are shownbelow.

    ______________________________________                                        Embodiment 1                                                                  r.sub.1 = 36.9278                                                             d.sub.1 = 10.6219                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 71.8243                                                             d.sub.2 = 4.9584                                                              r.sub.3 = -251.7459                                                           d.sub.3 = 3.4445                                                                              n.sub.2 = 1.80518                                                                        ν.sub.2 = 25.43                                 r.sub.4 = 35.6209                                                             d.sub.4 = 2.5517                                                              r.sub.5 = 42.5414                                                             d.sub.5 = 9.3616                                                                              n.sub.3 = 1.72000                                                                        ν.sub.3 = 41.98                                 r.sub.6 = -1096.6423                                                          d.sub.6 = 6.9452                                                              r.sub.7 = 95.5924                                                             d.sub.7 = 22.8878                                                                             n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                                 r.sub.8 = -51.5733                                                            d.sub.8 = 6.3414                                                              r.sub.9 = -29.3375                                                            d.sub.9 = 3.4448                                                                              n.sub.5 = 1.62606                                                                        ν.sub. 5 = 39.21                                r.sub.10 = -177.0669                                                          f = 100, |f.sub.5 |/f = 0.557, f.sub.123 /f.sub.4 =         ______________________________________                                        2.35                                                                          Embodiment 2                                                                  r.sub.1 = 37.2084                                                             d.sub.1 = 10.6181                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 69.9787                                                             d.sub.2 = 4.9411                                                              r.sub.3 = -221.5758                                                           d.sub.3 = 3.4433                                                                              n.sub.2 = 1.76182                                                                        ν.sub.2 = 26.55                                 r.sub.4 = 35.9272                                                             d.sub.4 = 2.5508                                                              r.sub.5 = 42.3315                                                             d.sub.5 = 9.3582                                                                              n.sub.3 = 1.71700                                                                        ν.sub.3 = 47.94                                 r.sub.6 = -2207.6200                                                          d.sub.6 = 6.9057                                                              r.sub.7 = 92.4645                                                             d.sub.7 = 23.1448                                                                             n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                                 r.sub.8 =  -51.0854                                                           d.sub.8 = 5.9603                                                              r.sub.9 = -29.4121                                                            d.sub.9 = 3.6069                                                                              n.sub.5 = 1.66998                                                                        ν.sub.5 = 39.32                                 r.sub.10 = -154.9387                                                          f = 100, |f.sub.5 |/f = 0.548, f.sub.123 /f.sub.4 =         ______________________________________                                        2.34                                                                          Embodiment 3                                                                  r.sub.1 = 37.7611                                                             d.sub.1 = 11.6679                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 73.0205                                                             d.sub.2 = 4.6672                                                              r.sub.3 = -244.9971                                                           d.sub.3 = 3.4483                                                                              n.sub.2 = 1.80518                                                                        ν.sub.2 = 25.43                                 r.sub.4 = 37.4424                                                             d.sub.4 = 2.5545                                                              r.sub.5 = 44.3299                                                             d.sub.5 = 9.3717                                                                              n.sub.3 = 1.72000                                                                        ν.sub.3 = 41.98                                 r.sub.6 = -656.8615                                                           d.sub.6 =  7.6324                                                             r.sub.7 = 99.1495                                                             d.sub.7 = 20.3054                                                                             n.sub.4 = 1.59739                                                                        ν.sub.4 = 34.48                                 r.sub.8 = -46.7657                                                            d.sub.8 = 5.4097                                                              r.sub.9 = -29.4558                                                            d.sub.9 = 7.5910                                                                              n.sub.5 = 1.62831                                                                        ν.sub.5 = 37.95                                 r.sub.10 = -282.7250                                                          f = 100, |f.sub.5 |/f = 0.529, f.sub.123 /f.sub.4 =         ______________________________________                                        2.39                                                                          Embodiment 4                                                                  r.sub.1 = 37.1666                                                             d.sub.1 = 11.6679                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 70.7724                                                             d.sub.2 = 4.6672                                                              r.sub.3 = -314.4423                                                           d.sub.3 = 3.4483                                                                              n.sub.2 = 1.80518                                                                        ν.sub.2 = 25.43                                 r.sub.4 = 36.3377                                                             d.sub.4 = 2.5545                                                              r.sub.5 = 43.7507                                                             d.sub.5 = 9.3717                                                                              n.sub.3 = 1.72000                                                                        ν.sub.3 = 41.98                                 r.sub.6 = -732.0967                                                           d.sub.6 = 7.6324                                                              r.sub.7 = 101.5236                                                            d.sub.7 = 22.7588                                                                             n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                                 r.sub.8 = -51.8227                                                            d.sub.8 = 5.4097                                                              r.sub.9 = -30.4738                                                            d.sub.9 = 6.8967                                                                              n.sub.5 = 1.62606                                                                        ν.sub.5 = 39.21                                 r.sub.10 = -225.3586                                                          f = 100, |f.sub.5 |/f = 0.571, f.sub.123 /f.sub.4 =         ______________________________________                                        2.12                                                                          Embodiment 5                                                                  r.sub.1 = 38.0501                                                             d.sub.1 = 11.6679                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 70.2468                                                             d.sub.2 = 4.6672                                                              r.sub.3 = -215.0498                                                           d.sub.3 = 3.4483                                                                              n.sub.2 = 1.80518                                                                        ν.sub.2 = 25.43                                 r.sub.4 = 41.1290                                                             d.sub.4 = 2.5545                                                              r.sub.5 = 44.6558                                                             d.sub.5 = 9.3717                                                                              n.sub.3 = 1.72000                                                                        ν.sub.3 = 43.70                                 r.sub.6 = -1355.6606                                                          d.sub.6 = 5.8781                                                              r.sub.7 = 92.5723                                                             d.sub.7 = 22.5159                                                                             n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                                 r.sub.8 = -50.0412                                                            d.sub.8 = 5.4097                                                              r.sub.9 = -28.1250                                                            d.sub.9 = 6.9005                                                                              n.sub.5 = 1.62606                                                                        ν.sub.5 = 39.21                                 r.sub.10 = -172.7446                                                          f = 100, |f.sub.5 |/f = 0.547, f.sub.123 /f.sub.4 =         ______________________________________                                        2.32                                                                          Embodiment 6                                                                  r.sub.1 = 37.5812                                                             d.sub.1 = 11.6238                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 =  40.76                                r.sub.2 = 72.9450                                                             d.sub.2 = 4.6496                                                              r.sub.3 = -228.4699                                                           d.sub.3 = 3.4352                                                                              n.sub.2 = 1.80518                                                                        ν.sub.2 = 25.43                                 r.sub.4 = 36.4531                                                             d.sub.4 = 2.5448                                                              r.sub.5 = 42.1673                                                             d.sub.5 = 9.3363                                                                              n.sub.3 = 1.72000                                                                        ν.sub.3 = 41.98                                 r.sub.6 = -816.9711                                                           d.sub.6 = 7.6036                                                              r.sub.7 = 96.4188                                                             d.sub.7 = 20.2247                                                                             n.sub.4 = 1.63980                                                                        ν.sub.4 = 34.48                                 r.sub.8 = -47.0295                                                            d.sub.8 = 5.3892                                                              r.sub.9 = -29.4885                                                            d.sub.9 = 7.5593                                                                              n.sub.5 = 1.72342                                                                        ν.sub.5 = 37.95                                 r.sub.10 = -215.6929                                                          f = 100, |f.sub.5 |/f = 0.480, f.sub.123 /f.sub.4 =         ______________________________________                                        2.58                                                                          Embodiment 7                                                                  r.sub.1 = 37.2670                                                             d.sub.1 = 10.6334                                                                             n.sub.1 = 1.84100                                                                        ν.sub.1 = 43.23                                 r.sub.2 = 71.1567                                                             d.sub.2 = 4.9483                                                              r.sub.3 = -211.9667                                                           d.sub.3 = 3.4483                                                                              n.sub.2 = 1.71736                                                                        ν.sub.2 = 29.51                                 r.sub.4 = 35.1359                                                             d.sub.4 = 2.5545                                                              r.sub.5 = 42.5678                                                             d.sub.5 = 9.3717                                                                              n.sub.3 = 1.71700                                                                        ν.sub.3 = 47.94                                 r.sub.6 = -5122.0812                                                          d.sub.6 = 6.9156                                                              r.sub.7 = 103.8046                                                            d.sub.7 = 23.1784                                                                             n.sub.4 = 1.59880                                                                        ν.sub.4 = 40.00                                 r.sub.8 = -49.0515                                                            d.sub.8 = 5.9690                                                              r.sub.9 = -29.9591                                                            d.sub.9 = 3.6149                                                                              n.sub.5 = 1.66390                                                                        ν.sub.5  = 39.32                                r.sub.10 = -152.3278                                                          f = 100, |f.sub.5 |/f = 0.568, f.sub.123 /f.sub.4 =         ______________________________________                                        2.37                                                                          Embodiment 8                                                                  r.sub.1 = 34.8858                                                             d.sub.1 = 11.6672                                                                             n.sub.1 = 1.86995                                                                        ν.sub.1 = 40.69                                 r.sub.2 = 69.5101                                                             d.sub.2 = 4.6669                                                              r.sub.3 = -382.0239                                                           d.sub.3 = 2.9028                                                                              n.sub.2 = 1.85563                                                                        ν.sub.2 = 23.66                                 r.sub.4 = 29.4132                                                             d.sub.4 = 2.5545                                                              r.sub.5 = 33.1008                                                             d.sub.5 = 9.9161                                                                              n.sub.3 = 1.72047                                                                        ν.sub.3 = 34.72                                 r.sub.6 = 1433.9817                                                           d.sub.6 = 7.8050                                                              r.sub.7 = 80.0037                                                             d.sub.7 = 19.3608                                                                             n.sub.4 = 1.66446                                                                        ν.sub.4 = 35.71                                 r.sub.8 = -43.0020                                                            d.sub.8 = 4.7013                                                              r.sub.9 = -27.2916                                                            d.sub.9 = 6.0628                                                                              n.sub.5 = 1.83400                                                                        ν.sub.5 = 37.16                                 r.sub.10 = -160.8388                                                          f = 100, |f.sub.5 |/f = 0.402, f.sub.123 /f.sub.4 =         ______________________________________                                        3.03                                                                          Embodiment 9                                                                  r.sub.1 = 35.7111                                                             d.sub.1 = 11.7178                                                                             n.sub.1 = 1.87588                                                                        ν.sub.1 = 43.49                                 r.sub.2 = 71.7423                                                             d.sub.2 = 4.6871                                                              r.sub.3 = -380.6859                                                           d.sub.3 = 2.9154                                                                              n.sub.2 = 1.82506                                                                        ν.sub.2 = 24.96                                 r.sub.4 = 29.4108                                                             d.sub.4 = 2.5655                                                              r.sub.5 = 33.6628                                                             d.sub.5 = 9.9591                                                                              n.sub.3 = 1.72047                                                                        ν.sub.3 = 34.72                                 r.sub.6 = 624.1191                                                            d.sub.6 = 7.839                                                               r.sub.7 = 80.3506                                                             d.sub.7 = 19.4396                                                                             n.sub.4 = 1.66446                                                                        ν.sub.4 = 35.71                                 r.sub.8 = -43.1884                                                            d.sub.8 = 4.7217                                                              r.sub.9 = -27.6775                                                            d.sub.9 = 6.0858                                                                              n.sub.5 = 1.83400                                                                        ν.sub.5 = 37.16                                 r.sub.10 = -156.5912                                                          f = 100, |f.sub.5 |/f = 0.412, f.sub.123 /f.sub.4 =         ______________________________________                                        3.13                                                                          Embodiment 10                                                                 r.sub.1 = 34.9347                                                             d.sub.1 = 11.6667                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 67.6624                                                             d.sub.2 = 4.6667                                                              r.sub.3 = -420.7331                                                           d.sub.3 = 2.9026                                                                              n.sub.2 = 1.84666                                                                        ν.sub.2 = 23.88                                 r.sub.4 = 29.4509                                                             d.sub.4 = 2.5543                                                              r.sub.5 = 33.5803                                                             d.sub.5 =  9.9157                                                                             n.sub.3 = 1.72047                                                                        ν.sub.3 = 34.72                                 r.sub.6 = 840.1923                                                            d.sub.6 = 7.8048                                                              r.sub.7 = 80.0000                                                             d.sub.7 = 19.3540                                                                             n.sub.4 = 1.66446                                                                        ν.sub.4 = 35.71                                 r.sub.8 = -43.0000                                                            d.sub.8 = 4.7015                                                              r.sub.9 = -27.8644                                                            d.sub.9 = 6.0581                                                                              n.sub.5 = 1.83400                                                                        ν.sub.5 = 37.16                                 r.sub.10 = -164.9675                                                          f = 100, |f.sub.5 |/f = 0.410, f.sub.123 /f.sub.4 =         ______________________________________                                        3.16                                                                          Embodiment 11                                                                 r.sub.1 = 37.2931                                                             d.sub.1 = 11.6694                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 73.2932                                                             d.sub.2 = 4.8627                                                              r.sub.3 = -161.2470                                                           d.sub.3 = 3.4488                                                                              n.sub.2 = 1.84666                                                                        ν .sub.2 = 23.88                                r.sub.4 = 36.8066                                                             d.sub.4 = 2.5549                                                              r.sub.5 = 42.2447                                                             d.sub.5 = 9.3730                                                                              n.sub.3 = 1.72047                                                                        ν.sub.3 = 34.72                                 r.sub.6 = -216.8284                                                           d.sub.6 = 7.6333                                                              r.sub.7 = 88.4469                                                             d.sub.7 = 20.3040                                                                             n.sub.4 = 1.66446                                                                        ν.sub.4 = 35.71                                 r.sub.8 = -47.4593                                                            d.sub.8 = 5.3801                                                              r.sub.9 = -29.5908                                                            d.sub.9 = 7.5891                                                                              n.sub.5 = 1.83400                                                                        ν.sub.5 = 37.16                                 r.sub.10 = -193.4414                                                          f = 100, |f.sub.5 |/f = 0.422, f.sub.123 /f.sub.4 =         ______________________________________                                        2.66                                                                          Embodiment 12                                                                 r.sub.1 = 34.5897                                                             d.sub.1 = 11.6678                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 68.2036                                                             d.sub.2 = 4.6671                                                              r.sub.3 = -469.2025                                                           d.sub.3 = 2.9029                                                                              n.sub.2 = 1.84666                                                                        ν.sub.2 = 23.88                                 r.sub.4 = 30.4475                                                             d.sub.4 = 2.5546                                                              r.sub.5 = 36.6517                                                             d.sub.5 = 9.9167                                                                              n.sub.3 = 1.72047                                                                        ν.sub.3 = 34.72                                 r.sub.6 = 1481.2730                                                           d.sub.6 = 7.842                                                               r.sub.7 = 86.3452                                                             d.sub.7 = 19.2011                                                                             n.sub.4 = 1.66446                                                                        ν.sub.4 = 35.71                                 r.sub.8 = -45.2419                                                            d.sub.8 = 5.0184                                                              r.sub.9 = -29.6013                                                            d.sub.9 = 6.1629                                                                              n.sub.5 = 1.83400                                                                        ν.sub.5 = 37.16                                 r.sub.10 = -167.4479                                                          f = 100, |f.sub.5 |/f = 0.440, f.sub.123 f.sub.4 =          ______________________________________                                        2.96                                                                          Embodiment 13                                                                 r.sub. 1 = 37.0605                                                            d.sub.1 = 11.6678                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 71.5043                                                             d.sub.2 = 4.6672                                                              r.sub.3 = -170.9580                                                           d.sub.3 = 3.4483                                                                              n.sub.2 = 1.84666                                                                        ν.sub.2 = 23.88                                 r.sub.4 = 36.9683                                                             d.sub.4 = 2.5546                                                              r.sub.5 = 42.4542                                                             d.sub.5 = 9.3717                                                                              n.sub.3 = 1.72047                                                                        ν.sub.3 = 34.72                                 r.sub.6 = -232.2169                                                           d.sub.6 = 7.6323                                                              r.sub.7 = 89.3367                                                             d.sub.7 = 20.3012                                                                             n.sub.4 = 1.66446                                                                        ν.sub.4 = 35.71                                 r.sub.8 = -46.6954                                                            d.sub.8 = 5.4097                                                              r.sub.9 = -29.6999                                                            d.sub.9 = 7.5880                                                                              n.sub.5 = 1.83400                                                                        ν.sub.5 = 37.16                                 r.sub.10 = -199.0312                                                          f = 100, |f.sub.5 |/f = 0.427, f.sub.123 /f.sub.4 =         ______________________________________                                        2.70                                                                      

In embodiments shown in the above, reference symbols r₁ through r₁₀respectively represent radii of curvature of respective lens surfaces,reference symbols d₁ through d₉ respectively represent thicknesses ofrespective lenses and airspaces between respective lenses, referencesymbols n₁, n₂, n₃, n₄ and n₅ respectively represent refractive indicesof respective lenses, and reference symbols ν₁, ν₂ ν₃, ν₄ and ν₅respectively represent Abbe's numbers of respective lenses.

As it is evident from the explanation given so far and respectiveembodiments, the present invention provides a photographic lens systemarranged compactly which comprises a front lens group located on theobject side and a rear lens group located on the image side and, at thesame time, which is arranged to have a wide field angle and favourablycorrected aberrations such as astigmatic difference, distortion, etc. byproviding a thick convex lens in rear of the stop.

When the lens system according to Embodiment 1 is rearranged to have thelens configuration as shown in FIG. 15, i.e., when the portioncorresponding to the plane-parallel plate in the thick lens is replacedwith an airspace, numerical data of that lens system become as shownbelow and aberration curves of said lens system become as shown in FIG.16.

    ______________________________________                                        r.sub.1 = 36.9278                                                             d.sub.1 = 10.6219                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 71.8243                                                             d.sub.2 = 4.9584                                                              r.sub.3 = -251.7459                                                           d.sub.3 = 3.4445                                                                              n.sub.2 = 1.80518                                                                        ν.sub.2 = 25.43                                 r.sub.4 = 35.6209                                                             d.sub.4 = 2.5517                                                              r.sub.5 = 42.5414                                                             d.sub.5 = 9.3616                                                                              n.sub.3 = 1.72000                                                                        ν.sub.3 = 41.98                                 r.sub.6 = -1096.6423                                                          d.sub.6 = 6.9452                                                              r.sub.7 = 95.5924                                                             d.sub.7 = 1.4439                                                                              n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                                 r.sub.7' = ∞                                                            d.sub.7' = 12.5573                                                            r.sub.8' = ∞                                                            d.sub.8' = 1.4439                                                                             n.sub.4 ' = 1.59270                                                                      ν.sub.4 '  = 35.29                              r.sub.8 = -51.5733                                                            d.sub.8 = 6.3414                                                              r.sub.9 = -29.3375                                                            d.sub.9 = 3.4448                                                                              n.sub.5 = 1.62606                                                                        ν.sub.5 = 39.21                                 r.sub.10 = -177.0669                                                          ______________________________________                                    

When aberration curves (FIG. 16) of the lens system having theabove-mentioned numerical data are compared with aberration curves ofEmbodiment 1 (FIG. 2), it is evident that aberrations, especiallyastigmatism and distortion, of the former lens system are aggravated.This clearly shows the effectiveness of the present invention,especially the effect attained by the use of the thick lens.

The lens system according to the present invention is arranged to befocused on an object at a short distance by simultaneously moving thefirst lens, which is a positive meniscus lens having a surfaceconcentric with the stop, and the fifth lens which is a negativemeniscus lens having a surface concentric with the stop. In other words,this focusing method is a combination of the focusing methods (3) and(5) mentioned before. When the first lens is moved, spherical aberrationbecomes negative and curvature of field becomes positive. On the otherhand, when the fifth lens is moved, spherical aberration becomesnegative and curvature of field also becomes negative. Therefore, byadequately selecting the amounts of movements of the first lens andfifth lens, it is possible to make the amount of variation of theoptical image position determined by spherical aberration approximatelyequal to that determined by curvature of field.

For example, when the lens system according to Embodiment 13 is focusedon an object at a short distance with the magnification 1/33 by movingthe first and fifth lenses, values of airspaces d₂ and d₈ become asfollows.

    d.sub.2 =5.36,d.sub.8 =5.94

At that time, aberration curves of said lens system become as shown inFIG. 17.

When the above-mentioned lens system according to Embodiment 13 isfocused on an object at the short distance by moving the rear lens only,the airspace d₈ becomes d₈ =6.30. Aberration curves in that case areshown in FIG. 18. At that time, both of spherical aberration andcurvature of field vary in the same direction compared with the statethat the same lens system is focused on an object at the infinitedistance. However, the amount of variation of curvature of field islarger compared with the amount of variation of spherical aberration.

On the other hand, when said lens system is focused by advancing thefront lens only, the airspace d₂ becomes d₂ =6.34. Aberration curves atthat time are shown in FIG. 19. As shown in this figure, sphericalaberration varies in the direction opposite to the direction ofvariation of curvature of field.

As described in the above, the optical image position determined bycurvature of field is deviated from the optical image positiondetermined by spherical aberration in both cases.

In compact cameras, the stop is fixed in most cases. Therefore, when theafore-mentioned focusing method to move the first and fifth lenses areadopted, the lens moving mechanism should be provided extending over toboth sides of the stop mechanism and, consequently, the lens movingmechanism becomes complicated. In case that the focusing method toadvance the front lens or front lens group is adopted, the lens movingmechanism becomes simple when the focusing mechanism is provided in thefront portion of the camera. Besides, when the focusing method to movethe fourth lens, i.e., the intermediate lens, or the focusing method tomove the fifth lens, i.e., the rear lens group, is adopted and thefocusing mechanism is provided in rear of the srop, the lens movingmechanism becomes simple and this is preferable especially in case of anautomatic focusing type camera.

I claim:
 1. A photographic lens system comprising a front lens group anda rear lens group, said front lens group comprising a first, second andthird lenses, said first lens being a positive meniscus lens arranged tobe convex toward the object side, said second lens being a biconcavelens, said third lens being a positive lens, said rear lens groupcomprising a fourth and fifth lens, said fourth lens being a biconvexlens, said fifth lens being a negative meniscus lens arranged to beconvex toward the image side, said photographic lens system beingarranged to fulfill the condition (1) shown below:

    0.15f<d.sub.7 <0.4f                                        (1)

where, reference symbol d₇ represents the thickness of the fourth lens,and reference symbol f represents the focal length of the lens system asa whole.
 2. A photographic lens system according to claim 1 furtherfulfilling the conditions (2) and (3) shown below:

    1.7<n.sub.2                                                ( 2)

    0.35f<|f.sub.5 |<0.6f,f.sub.5 <0         (3)

where, reference symbol n₂ represents the refractive index of the secondlens, and reference symbol f₅ represents the focal length of the fifthlens.
 3. A photographic lens system according to claim 2 furtherfulfilling the condition (4) shown below:

    0.25f<|r.sub.9 |<0.35f                   (4)

where, reference symbol r₉ represents the radius of curvature of thesurface on the object side of the fifth lens.
 4. A photographic lenssystem according to claim 3 further fulfilling the condition (5) shownbelow:

    0.4f<|r.sub.8 |<0.5f                     (5)

where, reference symbol r₈ represents the radius of curvature of thesurface on the image side of the fourth lens.
 5. A photographic lenssystem according to claim 1 further comprising a stop arranged betweensaid front lens group and said rear lens group wherein at least one lensconstituting said front lens group is arranged as a first movable lenscomponent and at least one lens constituting said rear lens group isarranged as a second moveble lens component, said first movable lenscomponent having refractive power with a sign different from the sign ofrefractive power of said second movable lens component, saidphotographic lens system being arranged to be focused by moving saidfirst and second movable lens components.
 6. A photographic lens systemaccording to claim 5 wherein said first movable lens component haspositive refractive power.
 7. A photographic lens system according toclaim 5 wherein said photographic lens system is arranged to be focusedby moving said first lens and said fifth lens.
 8. A photographic lenssystem according to claim 1 wherein said photographic lens system hasthe following numerical data:

    ______________________________________                                        r.sub.1 = 36.9278                                                             d.sub.1 = 10.6219                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 71.8243                                                             d.sub.2 = 4.9584                                                              r.sub.3 = -251.7459                                                           d.sub.3 = 3.4445                                                                              n.sub.2 = 1.80518                                                                        ν.sub.2 = 25.43                                 r.sub.4 = 35.6209                                                             d.sub.4 = 2.5517                                                              r.sub.5 = 42.5414                                                             d.sub.5 = 9.3616                                                                              n.sub.3 = 1.72000                                                                        ν.sub.3 = 41.98                                 r.sub.6 = -1096.6423                                                          d.sub.6 = 6.9452                                                              r.sub.7 = 95.5924                                                             d.sub.7 = 22.8878                                                                             n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                                 r.sub.8 = -51.5733                                                            d.sub.8 = 6.3414                                                              r.sub.9 = -29.3375                                                            d.sub.9 = 3.4448                                                                              n.sub.5 = 1.62606                                                                        ν.sub.5 =  39.21                                r.sub.10 = -177.0669                                                          f = 100, |f.sub.5 |/f = 0.557, f.sub.123 /f.sub.4 =         ______________________________________                                        2.35                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refractive indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 9. A photographic lens system according to claim 1 wherein saidphotographic lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 37.2084                                                             d.sub.1 = 10.6181                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 69.9787                                                             d.sub.2 = 4.9511                                                              r.sub.3 = -221.5758                                                           d.sub.3 = 3.4433                                                                              n.sub.2 = 1.76182                                                                        ν.sub.2 = 26.55                                 r.sub.4 = 35.9272                                                             d.sub.4 = 2.5508                                                              r.sub.5 = 42.3315                                                             d.sub.5 = 9.3582                                                                              n.sub.3 = 1.71700                                                                        ν.sub.3 = 47.94                                 r.sub.6 = -2207.6200                                                          d.sub.6 = 6.9057                                                              r.sub.7 = 92.4645                                                             d.sub.7 = 23.1448                                                                             n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                                 r.sub.8 = -51.0854                                                            d.sub.8 = 5.9603                                                              r.sub.9 = -29.4121                                                            d.sub.9 = 3.6096                                                                              n.sub.5 = 1.66998                                                                        ν.sub.5 =  39.32                                r.sub.10 = -154.9387                                                          f = 100, |f.sub.5 |/f = 0.548, f.sub.123 /f.sub.4 =         ______________________________________                                        2.34                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refracitve indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 10. A photographic lens system according to claim 1 wherein saidphotographic lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 37.7611                                                             d.sub.1 = 11.6679                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 73.0205                                                             d.sub.2 = 4.6672                                                              r.sub.3 = -244.9971                                                           d.sub.3 = 3.4483                                                                              n.sub.2 = 1.80518                                                                        ν.sub.2 = 25.43                                 r.sub.4 = 37.4424                                                             d.sub.4 = 2.5545                                                              r.sub.5 = 44.3299                                                             d.sub.5 = 9.3717                                                                              n.sub.3 = 1.72000                                                                        ν.sub.3 = 41.98                                 r.sub.6 = -656.8615                                                           d.sub.6 = 7.6324                                                              r.sub.7 = 99.1495                                                             d.sub.7 = 20.3054                                                                             n.sub.4 = 1.59739                                                                        ν.sub.4 = 34.48                                 r.sub.8 = -46.7657                                                            d.sub.8 = 5.4097                                                              r.sub.9 = -29.4558                                                            d.sub.9 = 7.5910                                                                              n.sub.5 = 1.62831                                                                        ν.sub.5 =  37.95                                r.sub.10 = -282.7250                                                          f = 100, |f.sub.5 |/f = 0.529, f.sub.123 /f.sub.4 =         ______________________________________                                        2.39                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refracitve indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 11. A photographic lens system according to claim 1 wherein saidphotographic lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 37.1666                                                             d.sub.1 = 11.6679                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 70.7724                                                             d.sub.2 = 4.6672                                                              r.sub.3 = -314.4423                                                           d.sub.3 = 3.4483                                                                              n.sub.2 = 1.80518                                                                        ν.sub.2 = 25.43                                 r.sub.4 = 36.3377                                                             d.sub.4 = 2.5545                                                              r.sub.5 = 43.7507                                                             d.sub.5 = 9.3717                                                                              n.sub.3 = 1.72000                                                                        ν.sub.3 = 41.98                                 r.sub.6 = -732.0967                                                           d.sub.6 = 7.6324                                                              r.sub.7 = 101.5236                                                            d.sub.7 = 22.7588                                                                             n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                                 r.sub.8 = -51.8227                                                            d.sub.8 = 5.4097                                                              r.sub.9 = -30.4738                                                            d.sub.9 = 6.8967                                                                              n.sub.5 = 1.62606                                                                        ν.sub.5 =  39.21                                r.sub.10 = -225.3586                                                          f = 100, |f.sub.5 |/f = 0.571, f.sub.123 /f.sub.4 =         ______________________________________                                        2.12                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refracitve indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 12. A photographic lens system according to claim 1 wherein saidphotographic lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 38.0501                                                             d.sub.1 = 11.6679                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 70.2468                                                             d.sub.2 = 4.6672                                                              r.sub.3 = -215.0498                                                           d.sub.3 = 3.4483                                                                              n.sub.2 = 1.80518                                                                        ν.sub.2 = 25.43                                 r.sub.4 = 41.1290                                                             d.sub.4 = 2.5545                                                              r.sub.5 = 44.6558                                                             d.sub.5 = 9.3717                                                                              n.sub.3 = 1.72000                                                                        ν.sub.3 = 43.70                                 r.sub.6 = -1355.6606                                                          d.sub.6 = 5.8781                                                              r.sub.7 = 92.5723                                                             d.sub.7 = 22.5159                                                                             n.sub.4 = 1.59270                                                                        ν.sub.4 = 35.29                                 r.sub.8 = -50.0412                                                            d.sub.8 = 5.4097                                                              r.sub.9 = -28.1250                                                            d.sub.9 = 6.9005                                                                              n.sub.5 = 1.62606                                                                        ν.sub.5 =  39.21                                r.sub.10 = -172.7446                                                          f = 100, |f.sub.5 |/f = 0.547, f.sub.123 /f.sub.4 =         ______________________________________                                        2.32                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refractive indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 13. A photographic lens system according to claim 1 wherein saidphotographic lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 37.5812                                                             d.sub.1 = 11.6238                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 72.9450                                                             d.sub.2 = 4.6496                                                              r.sub.3 = -228.4699                                                           d.sub.3 = 3.4352                                                                              n.sub.2 = 1.80518                                                                        ν.sub.2 = 25.43                                 r.sub.4 = 36.4531                                                             d.sub.4 = 2.5448                                                              r.sub.5 = 42.1673                                                             d.sub.5 = 9.3363                                                                              n.sub.3 = 1.72000                                                                        ν.sub.3 = 41.98                                 r.sub.6 = -816.9711                                                           d.sub.6 = 7.6036                                                              r.sub.7 = 96.4188                                                             d.sub.7 = 20.2247                                                                             n.sub.4 = 1.63980                                                                        ν.sub.4 = 34.48                                 r.sub.8 = -47.0295                                                            d.sub.8 = 5.3892                                                              r.sub.9 = -29.4885                                                            d.sub.9 = 7.5593                                                                              n.sub.5 = 1.72342                                                                        ν.sub.5 =  37.95                                r.sub.10 = -215.6929                                                          f = 100, |f.sub.5 |/f = 0.480, f.sub.123 /f.sub.4 =         ______________________________________                                        2.58                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refractive indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 14. A photographic lens system according to claim 1 wherein saidphotographic lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 37.2670                                                             d.sub.1 = 10.6334                                                                             n.sub.1 = 1.84100                                                                        ν.sub.1 = 43.23                                 r.sub.2 = 71.1567                                                             d.sub.2 = 4.9483                                                              r.sub.3 = -211.9667                                                           d.sub.3 = 3.4483                                                                              n.sub.2 = 1.71736                                                                        ν.sub.2 = 29.51                                 r.sub.4 = 35.1359                                                             d.sub.4 = 2.5545                                                              r.sub.5 = 42.5678                                                             d.sub.5 = 9.3717                                                                              n.sub.3 = 1.71700                                                                        ν.sub.3 = 47.94                                 r.sub.6 = -5122.0812                                                          d.sub.6 = 6.9156                                                              r.sub.7 = 103.8046                                                            d.sub.7 = 23.1784                                                                             n.sub.4 = 1.59880                                                                        ν.sub.4 = 40.00                                 r.sub.8 = -49.0515                                                            d.sub.8 = 5.9690                                                              r.sub.9 = -29.9591                                                            d.sub.9 = 3.6149                                                                              n.sub.5 = 1.66390                                                                        ν.sub.5 =  39.32                                r.sub.10 = -152.3278                                                          f = 100, |f.sub.5 |/f = 0.568, f.sub.123 /f.sub.4 =         ______________________________________                                        2.37                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refractive indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 15. A photofraphic lens system according to claim 1 wherein saidphotographic lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 34.8858                                                             d.sub.1 = 11.6672                                                                             n.sub.1 = 1.86995                                                                        ν.sub.1 = 40.69                                 r.sub.2 = 69.5101                                                             d.sub.2 = 4.6669                                                              r.sub.3 = -382.0239                                                           d.sub.3 = 2.9028                                                                              n.sub.2 = 1.85563                                                                        ν.sub.2 = 23.66                                 r.sub.4 = 29.4132                                                             d.sub.4 = 2.5545                                                              r.sub.5 = 33.1008                                                             d.sub.5 = 9.9161                                                                              n.sub.3 = 1.72047                                                                        ν.sub.3 = 34.72                                 r.sub.6 = 1433.9817                                                           d.sub.6 = 7.8050                                                              r.sub.7 = 80.0037                                                             d.sub.7 = 19.3608                                                                             n.sub.4 = 1.66446                                                                        ν.sub.4 = 35.71                                 r.sub.8 = -43.0020                                                            d.sub.8 = 4.7013                                                              r.sub.9 = -27.2916                                                            d.sub.9 = 6.0628                                                                              n.sub.5 = 1.83400                                                                        ν.sub.5 = 37.16                                 r.sub.10 = -160.8388                                                          f = 100, |f.sub.5 |/f = 0.402, f.sub.123 /f.sub.4 =         ______________________________________                                        3.03                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refractive indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 16. A photographic lens system according to claim 1 wherein saidphotographic lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 35.7111                                                             d.sub.1 = 11.7178                                                                             n.sub.1 = 1.87588                                                                        ν.sub.1 = 43.49                                 r.sub.2 = 71.7423                                                             d.sub.2 = 4.6871                                                              r.sub.3 = -380.6859                                                           d.sub.3 = 2.9154                                                                              n.sub.2 = 1.82506                                                                        ν.sub.2 = 24.96                                 r.sub.4 = 29.4108                                                             d.sub.4 = 2.5655                                                              r.sub.5 = 33.6628                                                             d.sub.5 = 9.9591                                                                              n.sub.3 = 1.72047                                                                        ν.sub.3 = 34.72                                 r.sub.6 = 624.1191                                                            d.sub.6 = 7.839                                                               r.sub.7 = 80.3506                                                             d.sub.7 = 19.4396                                                                             n.sub.4 = 1.66446                                                                        ν.sub.4 = 35.71                                 r.sub.8 = -43.1884                                                            d.sub.8 = 4.7217                                                              r.sub.9 = -27.6775                                                            d.sub.9 = 6.0858                                                                              n.sub.5 = 1.83400                                                                        ν.sub.5 = 37.16                                 r.sub.10 = -156.5912                                                          f = 100, |f.sub.5 |/f = 0.412, f.sub.123 /f.sub.4 =         ______________________________________                                        3.13                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refractive indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 17. A photographic lens system according to claim 1 wherein saidphotographic lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 34.9347                                                             d.sub.1 = 11.6667                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 67.6624                                                             d.sub.2 = 4.6667                                                              r.sub.3 = -420.7331                                                           d.sub.3 = 2.9026                                                                              n.sub.2 = 1.84666                                                                        ν.sub.2 = 23.88                                 r.sub.4 = 29.4509                                                             d.sub.4 = 2.5543                                                              r.sub.5 = 33.5803                                                             d.sub.5 = 9.9157                                                                              n.sub.3 = 1.72047                                                                        ν.sub.3 = 34.72                                 r.sub.6 = 840.1923                                                            d.sub.6 = 7.8048                                                              r.sub.7 = 80.0000                                                             d.sub.7 = 19.3540                                                                             n.sub.4 = 1.66446                                                                        ν.sub.4 = 35.71                                 r.sub.8 = -43.0000                                                            d.sub.8 = 4.7015                                                              r.sub.9 = -27.8644                                                            d.sub.9 = 6.0581                                                                              n.sub.5 = 1.83400                                                                        ν.sub.5 = 37.16                                 r.sub.10 = -164.9675                                                          f = 100, |f.sub.5 |/f = 0.410, f.sub.123 /f.sub.4 =         ______________________________________                                        3.16                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and arispacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refractive indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 18. A photographic lens system according to claim 1 wherein saidphotographic lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 37.2931                                                             d.sub.1 = 11.6694                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 73.4932                                                             d.sub.2 = 4.8627                                                              r.sub.3 = -161.2470                                                           d.sub.3 = 3.4488                                                                              n.sub.2 = 1.84666                                                                        ν.sub.2 = 23.88                                 r.sub.4 = 36.8066                                                             d.sub.4 = 2.5549                                                              r.sub.5 = 42.2447                                                             d.sub.5 = 9.3730                                                                              n.sub.3 = 1.72047                                                                        ν.sub.3 = 34.72                                 r.sub.6 = -216.8284                                                           d.sub.6 = 7.6333                                                              r.sub.7 = 88.4469                                                             d.sub.7 = 20.3040                                                                             n.sub.4 = 1.66446                                                                        ν.sub.4 = 35.71                                 r.sub.8 = -47.4593                                                            d.sub.8 = 5.3801                                                              r.sub.9 = -29.5908                                                            d.sub.9 = 7.5891                                                                              n.sub.5 = 1.83400                                                                        ν.sub.5 =  37.16                                r.sub.10 = -193.4414                                                          f = 100, |f.sub.5 |/f = 0.422, f.sub.123 /f.sub.4 =         ______________________________________                                        2.66                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refractive indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 19. A photographic lens system according to claim 1 wherein saidphotographic lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 34.5897                                                             d.sub.1 = 11.6678                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 68.2036                                                             d.sub.2 = 4.6671                                                              r.sub.3 = -469.2025                                                           d.sub.3 = 2.9029                                                                              n.sub.2 = 1.84666                                                                        ν.sub.2 = 23.88                                 r.sub.4 = 30.4475                                                             d.sub.4 = 2.5546                                                              r.sub.5 = 36.6517                                                             d.sub.5 = 9.9167                                                                              n.sub.3 = 1.72047                                                                        ν.sub.3 = 34.72                                 r.sub.6 = 1481.2730                                                           d.sub.6 = 7.842                                                               r.sub.7 = 86.3452                                                             d.sub.7 = 19.2011                                                                             n.sub.4 = 1.66446                                                                        ν.sub.4 = 35.71                                 r.sub.8 = -45.2419                                                            d.sub.8 = 5.0184                                                              r.sub.9 = -29.6013                                                            d.sub.9 = 6.1629                                                                              n.sub.5 = 1.83400                                                                        ν.sub.5 = 37.16                                 r.sub.10 = -167.4479                                                          f = 100, |f.sub.5 |/f = 0.440, f.sub.123 /f.sub.4 =         ______________________________________                                        2.96                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refractive indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 20. A photographic lens system according to claim 1 wherein saidphotographic lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 37.0605                                                             d.sub.1 = 11.6678                                                                             n.sub.1 = 1.88300                                                                        ν.sub.1 = 40.76                                 r.sub.2 = 71.5043                                                             d.sub.2 = 4.6672                                                              r.sub.3 = -170.9580                                                           d.sub.3 = 3.4483                                                                              n.sub.2 = 1.84666                                                                        ν.sub.2 = 23.88                                 r.sub.4 = 36.9683                                                             d.sub.4 = 2.5546                                                              r.sub.5 = 42.4542                                                             d.sub.5 = 9.3717                                                                              n.sub.3 = 1.72047                                                                        ν.sub.3 = 34.72                                 r.sub.6 = -232.2169                                                           d.sub.6 = 7.6232                                                              r.sub.7 = 89.3367                                                             d.sub.7 = 20.3012                                                                             n.sub.4 = 1.66446                                                                        ν.sub.4 = 35.71                                 r.sub.8 = -46.6954                                                            d.sub.8 = 5.4097                                                              r.sub.9 = -29.6999                                                            d.sub.9 = 7.5880                                                                              n.sub.5 = 1.83400                                                                        ν.sub.5 =  37.16                                r.sub.10 = -199.0312                                                          f = 100, |f.sub.5 |/f = 0.427, f.sub.123 /f.sub.4 =         ______________________________________                                        2.70                                                                      

where, reference symbols r₁ through r₁₀ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₉respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₅ respectivelyrepresent refracitve indices of respective lenses, and reference symbolsν₁ through ν₅ respectively represent Abbe's numbers of respectivelenses.
 21. A photographic lens system according to claim 6 wherein saidphotographic lens system is arranged to be focused by moving said firstlens and said fifth lens.